Yarn texturing method



J. K. HUGHES YARN TEXTURING METHOD Aug 11, 1970 Filed Dec.

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J. K HUGHES ATTORNEYS United States Patent 3,523,345 YARN TEXTURING METHOD James K. Hughes, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Dec. 18, 1967, Ser. No. 691,600 Int. Cl. D02g 1/00 U.S. Cl. 28-72.1 Claims ABSTRACT OF THE DISCLOSURE Oriented thermoplastic yarn is textured by heating the yarn at intervals along its length on one side only to set up a temperature gradient across the yarn section, inducing different degrees of contraction on opposite sides of the yarn.

In one aspect, this invention relates to texturing yarns. In another aspect, the invention relates to intermittently crimping thermoplastic yarn. In another aspect, the invention relates to randomly crimping synthetic filaments.

Various types of synthetic fibers are used in the manufacture of textiles, and, in many instances, it is desirable to crimp such fibers. Many methods of crimping or texturing yarns are known, such as jet crimping, edge crimping, stuffer box crimping, gear crimping, and the like. When crimped thermoplastic filaments are subjected to elevated temperatures, they become set and retain the crimp at temperatures below the setting temperature. thus providing extensibility in the yarn as well as increased bulk and covering power.

Some methods of crimping produce a more or less uniform crimp. Yarns fashioned from filaments having a uniform or regular crimp have a low degree of bulk because of the tendency of individual filaments to line up in phase and become packed. The appearance of woven goods prepared from yarn of this type is not always satis factory because of the discernible pattern resulting from the regularity of the crimp.

By the practice of the invention, wherein a temperature gradient is imposed across the cross section of a thermoplastic yarn at intervals on the yarn length, there is produced a crimped yarn having bulk and other desirable properties.

Accordingly, it is an object of the invention to provide a method of crimping yarn.

Another object of the invention is to intermittently crimp yarn at random or regular points along the length of the yarn.

Another object of the invention is to provide a method for modulating the amplitude and/or the frequency of crimps imparted to a synthetic filament to produce a filament having a nonuniform or irregular crimp.

These and other objects of the invention will be apparent to one skilled in the art upon consideration'of the following specification, drawings, and appended claims.

FIG. 1 is a cross-sectional view of a filament.

FIGS. 2 and 3 illustrate a length of crimped yarn obtained by practice of the invention.

FIG. 4 is a schematic illustration of apparatus utilized in the practice of the invention.

FIG. 5 is a side view of apparatus used to randomly crimp yarn according to the invention.

FIG. 6 is a perspective illustration of another type of apparatus utilized in the practice of the invention.

According to the invention, there is provided a method of texturing synthetic thermoplastic yarn comprising heating the yarn at intervals along its length in a manner such that a temperature gradient is set up across the yarn cross section, inducing opposite sides of the yarn to contract different amounts, and cooling the heat-treated yarn under a tension allowing at least a part of the induced contraction to occur. In one embodiment, the. heating is accomplished while the yarn is under a tension sufficient to prevent any substantial contraction or elongation of the yarn.

Yarn as used in the description of the invention, is intended to include single filaments as well as a plurality of filaments. The expression cooling is intended to include allowing the yarn to cool.

Oriented thermoplastic filaments will contract in length when subjected to elevated temperatures. The amount of contraction is a function of the temperature to which the filament is heated. The present invention utilizes the heat shrinkage or contraction characteristics of oriented thermoplastic filaments to impart an intermittent crimp to the yarn. By intermittently heating the filament on one side only, a temperature gradient is set up across the filament cross section. This difference in temperature through the filament section causes opposite sides of the filament to contract different amounts, the hottest side conracting more than the cooler side. The differential contraction results in the crimp imparted to the filament.

The oriented filaments to which the process of the in vention is applicable are those resulting from the melt spinning of filament-forming thermoplastic materials. Suitable filament-forming thermoplastic materials include polyolefins, such as polypropylene and polyethylene, polyamides, polysulfonamides, polyesters, polyacrylonitriles and the like. The filaments can be oriented by any conven tional method such as drawing at elevated temperature. The ratio of the drawn length to the original length is usually at least 3:1 and is generally in the range of 4:1 to 16:1.

The temperature to which the oriented filament is heated on one side will depend upon the particular thermoplastic comprising the filament and the degree of contraction desired. The temperature will usually be below the melting point of the thermoplastic material.

During heating, the yarn is maintained under a tension great enough to prevent any substantial contraction of the yarn yet low enough that there is no substantial elongation of the yarn. It is desirable to avoid high tensions which result in elongation of the yarns, since, previous to heat treatment, the yarn has been processed and oriented under conditions imparting characteristics which are desired to be retained in the yarn.

In one embodiment of the invention, the oriented yarn is heated at intervals along its length by focusing radiant energy on one side of the yarn which is dissipated through the yarn cross section in the form of heat to create the desired temperature gradient. One suitable source of radiant energy is the laser; the use of a laser is especially advantageous because of its ability to supply large amounts of energy to very small areas. Any of the gas, liquid, or solid lasers known in the industry can be used in the process of the nivention. The radiant energy can be in the infrared, Visible or ultraviolet region. The energy can be pulsed or modulated to produce the intermittent crimp, or the yarn can be intermittently passed through a continuous beam of energy.

In another embodiment, the oriented yarn is heated at intervals on its length by intermittent contact with a hot surface whereby heat is conducted from one side of the yarn to the other, creating the desired temperature gradient. One method of contact heating is to pass the yarn over a rotating cylinder having surface portions which are heated. In some instances, it may be advantageous to utilize a cooled nip roll in combination with the heated rotating cylinder to cool one side of the yarn while providing good contact with the heated portions of the cylinder.

Referring now to the drawing, some embodiments of the invention will be described in detail. FIG. 1 illustrates a filament, denoted generally as 10, is cross section. The filament is heated on one side, for example, side 11 to a desired elevated temperature and as the heat is conducted through the filament to the opposite side 12, there is created a temperature gradient which results in the differential contraction of the filament. The illustrated filament has a round cross section but differential contraction can be induced in filaments of noncircular cross section in like manner.

FIG. 2 illustrates a length of fiber 15, which was heated on one side only in the portions designated 16 and 17 to impart an intermittent helical crimp. The number of coils, of course, depend upon the degree of heating and the length of the interval which is heated. If desired a portion 16 can be heated on one side and a portion 17 heated on the opposite side, for example at 180 on the yarn cross section.

FIG. 3 illustrates a length of fiber 20 which has been heated at points 21, 22, 23, and 24 of an interval denoted generally as 25. Points along the yarn length in intervals 26 and 27 have been similarly treated. The curvilinear crimp is obtained by heating first on one side, such as at point 21, and then on the other side, such as at point 22. It is possible to obtain a curvilinear crimp by heating points on the yarn cross section which are 90 out of phase with each other. The amplitude of the crimp is varied by varying the intensity of the heat treatment at different points. The thermoplastic filament 20 has been illustrated as being crimped at random intervals but, of course, the crimps can be imparted at regular intervals if desired.

FIG. 4 is a schematic illustration of apparatus used in practice of the invention wherein there is represented a thermoplastic yarn 30 contained on a bobbin 31, guide ring 32, feed rollers 33 and 34, grooved guide cylinder 35, take-up rollers 36 and 37, and package roll 38. There is also represented a source of radiant energy, such as a laser 41, and lens means 42 for focusing the energy. In the practice of the invention, the yarn 30 is passed from bobbin 31 through guide ring 32, between feed rollers 33 and 34, about grooved cylinder 35, between take-up rollers 36 and 37 and onto package roll 38. The rollers rotate in the direction shown by the arrows: rollers 33, 34, and 35 rotating at the same peripheral speed with rollers 36 and 37 rotating at a slightly higher peripheral speed to maintain the desired degree of tension. The yarn is fed at an angle such that the multifilament bundle is spread out in the groove of guide cylinder 35. The groove in cylinder 35 is inclined at an acute angle to the longitudinal axis of cylinder 35 to cause the path of the yarn through the groove to move back and forth in a direction parallel to the longitudinal axis of cylinder 35. In this embodiment, the laser 41 is regularly or randomly pulsed by means, not shown, and the energy is focused by lens 42 at the outer edge of the filament cross section as the yarn passes through the guide groove of cylinder 35. Cylinder 35 can be provided with internal cooling means so that the side of the yarn in contact with the cylinder is cooled while the opposite side is intermittently heated by the pulsating radiant energy. The yarn is passed from take-up rollers 36 and 37 to package roll 38 under little or no tension, allowing the yarn to cool and contract.

FIG. illustrates apparatus used in conjunction with a continuously focused beam of radiant energy 45 which intermittently heats one side of a monofilament 46 as it wanders between shoulders 47 and 48 across the smooth surface of rotating cylinder 49, as a result of the yarn being passed around cylinder 49 at an acute angle to the longitudinal axis of cylinder 49. The filament can be allowed to twist as it passes across the smooth surface, thus differing points on the cross section of the yarn will be presented to the focused energy as the yarn passes into and out of the energy beam. The crimp thus imparted is random to a certain degree.

With reference to FIG. 6, a synthetic thermoplastic yarn 30 is passed from a source of supply, not shown, under a guide bar 51 between feed rollers 52 and 53, around heated roller 54, between take-up rollers 56 and 57, and onto a package roll 58.

Roller 54 is provided with spaced-apart heating wires 55 parallel to the axis of the roller to heat, by contact, one side of yarn 30. The wires can be spaced or positioned at regular or irregular intervals about the surface of the cylinder. The wires are connected to a power source, not shown, and can be heated to the same temperature to impart a crimp having a uniform amplittude or they can be heated to different degrees to provide a crimp of varying amplitude. If desired, a cooled cylinder 59 can be provided to operate with the heated cylinder 54 to cool one side of the filament while ensuring contact of the other side with the heated portions of the cylinder.

The variations in filament or yarn texture which can be produced by the practice of the invention are numerous. Kinking or curling in any desired direction can be imparted in the filament by the method described. The amplitude and frequency of crimping can be easily varied by relating the time interval of heating to the rate at which the yarn passes through the heating zone. The frequency of crimping can be varied according to a predetermined pattern, which is ultimately random in nature, while heating the yarn to the same temperature at each interval to obtain crimping of constant amplitude. In a similar manner the frequency can be controlled to obtain a uniform periodic crimp while varying the amount of heating to impart a crimp of random ampltiude. Known means, such as a random timer or stepping switch, can be used in combination with the heating means to obtain the desired random characteristics. Reasonable modifications and variations are within the scope of the invention.

That which is claimed is:

1. A method of producing intermittently crimped oriented thermoplastic yarn, comprising passing a drawn, oriented thermoplastic yarn into contact with and at least partially around the periphery of a cylinder at an acute angle to the longitudinal axis of said cylinder; rotating said cylinder to cause the path of said drawn, oriented thermoplastic yarn to mave back and forth in a direction parallel to the axis of said cylinder; cooling the surface of said cylinder so that the side of said drawn, oriented thermoplastic yarn in contact with said cylinder is cooled; focusing a beam of radiant energy onto an area of said cylinder traversed by said path to intermittently heat said drawn, oriented thermoplastic yarn only at intervals along its length on one side thereof in a manner such that a temperature gradient is set up across the yarn cross section at the thus heated regions to induce opposite sides of the yarn to contact to different degrees, while maintaining the yarn under a tension great enough to prevent any substantial contraction of the yarn during said heating but low enough so that there is no substantial elongation of the yarn during said heating; and then cooling the thus heat-treated yarn under a tension allowing at least a part of the induced contraction to occur.

2. The method of claim 1 wherein the highest temperature of said temperature gradient is below the melting point of said thermoplastic material.

1 3a The method of claim 1 wherein said beam is moduate 4. The method of claim 1 wherein said beam is pro duced by a laser.

5. The method of claim 1 wherein said intervals along the yarn length are periodic.

6. The method of claim 1 wherein said intervals are random.

7. The method of claim 1 wherein different intervals along the length of said yarn are heated to different temperatures to produce a crimp having a varying amplitude.

8. The method of claim 1 wherein said cylinder is provided with a groove in the cylindrical surface thereof inclined at an angle to the axis of said cylinder, and said yarn passes along said groove.

9. The method of claim 8 wherein said yarn comprises a bundle of a plurality of filaments and wherein said yarn is fed to said cylinder at an angle such that said bundle is spread out in said groove.

10. The method of claim 1 wherein said cylinder is provided with a smooth cylinder surface bounded by an 10 outwardly pro ectmg shoulder at each end thereof, and

wherein said yarn is twisted as it passes across said smooth cylindrical surface to present differing points on the cross section of said yarn to said beam as said yarn passes into and out of said beam.

References Cited UNITED STATES PATENTS 3,292,270 12/1966 Spunt.

6 3,175,196 3/1965 Lee et al. 340173 3,347,036 10/1967 Daniel 2872.1

3,343,207 9/ 1967 Mottern et al. 3,374,302 3/1968 Stanley. 5 3,047,932 8/1962 Pittman et al. 3,095,630 7/1963 Pittman. 3,176,373 4/ 1965 Taylor. 3,374,514 3/1968 McClure.

FOREIGN PATENTS 763,156 7/1967 Canada. 808,213 1/ 1959 Great Britain. 1,028,979 5/ 1966 Great Britain.

15 ROBERT R. MACKEY, Primary Examiner U.S. Cl. X.R. 

